Radar is frequently used to detect atmospheric turbulence. A typical application is to use radar installed on an aircraft to detect hazardous turbulence and display its relative location with respect to the aircraft so that the pilot can avoid it. The detection of turbulence using radar involves the processing of signals transmitted by the radar and scattered from water droplets embedded in the turbulent air. Signal processing is performed to produce the Doppler second moment of the signal, which is then related to the degree of hazard that would be expected from flying through the turbulent area.
Standard practice in using radar to estimate turbulence hazard is to sweep the radar antenna at a pilot selected tilt angle (elevation angle with respect to the horizon), or an automatically selected tilt. The turbulence signal processing is performed as the signals are received, and related spatially to the range and pointing direction. As the antenna is scanned back and forth in azimuth, the turbulence is re-detected each time the antenna sweeps past the turbulent parcel of air. Atmospheric turbulence has some persistence spatially and temporally. That is, a parcel of turbulent air moves relatively slowly (with respect to the time scale of an antenna scan). Also, its intensity changes relatively slowly. By re-detecting the turbulence on every antenna scan, the standard radar cannot take advantage of previous measurements to improve the quality of the estimate of the turbulence hazard.
Because radar detection requires the presence of water droplets of sufficient size, radar is most useful for detecting turbulence associated with convection. The vertical motions caused by convection are responsible for generating the turbulence. As a result, the regions of turbulent air typically have some vertical extent that is not well reflected in the turbulence measurement from a radar scanning at a single tilt.
Therefore, there exists a need to more accurately identify turbulence weather information.